This section is from the book "Meals Medicinal", by W. T. Fernie. Also available from Amazon: Meals Medicinal: With "Herbal Simples" Curative Foods From the Cook in Place of Drugs From the Chemist.
A demulcent drink made from Linseed, the seeds of flax, is most helpful against catarrhal soreness of the chest, with irritating hard cough. These seeds are very rich in oil, containing nearly four ounces in every pound of the seed, together with gum, acetic acid, acetate of potash, and muriate of potash. A Linseed tea may be concocted from the ground seed with cold water, one ounce to the tumblerful, steeped all night, and then poured off (after being stirred) in the morning, and presently allowed to settle. This cold tea is sustaining for consumptive patients. If Linseed is ground into meal, and macerated in boiling water, the abundant mucilage to be obtained from the outer skins makes a poultice as prepared therefrom, emollient, and soothing when applied very hot. The Linseed oil has laxative properties as a medicine; furthermore, when mixed with lime water, it makes an admirably protective covering for recent burns, and scalds. A more elaborate Linseed tea may be thus concocted: Wash two ounces of linseed, putting it into a small strainer, and pouring cold water through it, then pare off as thinly as possible the yellow rind of half a lemon; to the linseed and lemon rind add a quart of cold water, and allow them to simmer over the fire for an hour and a half; strain away the seeds, and to each half pint of tea add a teaspoonful of sugar, or sugar candy, with some fresh lemon juice, in the proportion of the juice of one lemon to each pint of the tea.
Powdered sugar-candy with white of egg, as an emulsion, is used remedially in Germany. To make sugar-candy thin strings are suspended in a very strong solution of sugar, which is then left standing in a cool place until the candy forms as crystals about the strings (also on the sides of the vessel).
After the linseed oil has been expressed from the seeds, then their refuse is oil cake, a well known fattening food for cattle. Linseed (linum usitatissimum) was taken in cookery by the ancient Greeks and Romans, but it is difficult of digestion, and affords but little proteid nourishment, whilst provoking troublesome flatulence. In the sixteenth century, during a scarcity of wheat, the inhabitants of Middleburgh had recourse to linseed for making cakes, but the death of many citizens was caused thereby, bringing about in those who partook of the cakes dreadful swellings on the body and face. In Dundee, a hank of (flax) yarn is worn round the loins as a cure for lumbago, and girls may be seen with a single thread of this yarn round the head as an infallible specific for tic doloureux. Linseed oil is substituted for lard on fast days by Italian peasants and labourers.